# Op-Amp working principle

In the op-amp working principle I was told that if I have a certain input voltage at the non inverting pin, then the inverting pin will also be forced to have that voltage and hence if I attach a feedback impedance to the output, then the output voltage will align itself in such a way that KVL and KCL are conserved along with reflection of a followed voltage at the inverting pin. My question is, why does this reflection of similar voltage at the inverting pin happen depending on the non-inverting pin? Can I also reverse the ideology? That is if I were to have a voltage V0 at the inverting pin and attach a feedback at the non-inverting pin, will it follow the voltage at the inverting pin?

What you were told is not theoretically correct. You have to change the way o thinking what really happens. It is the feedback loop that can force IN-=IN+ , not IN-=IN+ that makes the loop work.

The condition IN-=IN+ des not happen magically.

Start thinking that $Vout=A_0(IN_+-IN_-)$ where $A_0=10^6$

This is the IN\Out relation of an open circuit (not in a feedback loop) OPAMP

When you close the OPAMP in a negative feedback loop with resistance $R_1,R_2$ this relation is still valid but the loop will change everithing

When you apply a voltage to the IN+ of the OPAMP, at time $T=0^+$ its output will saturate to $V^+$(positive rail) as $IN_+=Vin$, $IN_-=0$ and so $Vout=10^6(Vin-0)=too much$.

Then, thanks to the feedback loop $IN_-$ will go from $0$ to $V_{out}*\frac{R1}{R_1+R_2}=V^+*\frac{R1}{R_1+R_2}$.

What happen next is that the value of $V_{out}$ will change as the value of $(IN_+-IN_-)$ chaged thanks to the loop. As a conseguange the value of $IN_-$ will change again and again Vout and $IN_-$ again and so on.....

At this point you should understand were we are going, as we have a negative feedback Vout and $IN_-$ will change until you reach a point of equilibrium. The point of equilibrium is when you have $IN_-=IN+$

This ideology can be reversed but be carful that in the other case the loop becomes a positive one and instead of reducing to $0$ the difference $IN_--IN+$ this will increase untill you reach another equilibrium point that is in this case $V_{out}=V^+$

No, reversing the idea results in positive feedback, instead of the negative feedback that's required for the principle you're talking about to hold.